Make common_sql_weight employ standard SQL functions for the timestamp
difference in seconds.
Also replace UTC_TIMESTAMP in the MariaDB-specific part with CURRENT_TIMESTAMP
as it is the only occurence and GNU social sets UTC as a default timezone.
In a delete_orphan_files.php script simplify the main query considerably.
In clean_profiles.php stop using COUNT as if it is ANY, that is unnecessary
punishment for the database. Instead implement the anti-join with a
left outer join.
In Autocomplete and Activitypub_profile use joins instead of a WHERE OR
anti-pattern for the semi-joins.
In lib/ui/galleryaction.php replace a CROSS JOIN with an INNER JOIN.
In actions/sup.php remove a redundant subquery: WHERE is applied before
grouping either way.
The code used to operate under the assumption that MariaDB doesn't support
quoting identifiers. Not only is that not exactly true, but MariaDB has
reserved keywords that cannot be used as table or column names unquoted.
